Embodiments described herein relate to an exhaust gas flow divider for a turbocharger turbine housing.
Back pressure developed by exhaust gases can be used to develop a retarding force on an engine, known as engine braking. The exhaust gas back pressure can be developed at a turbocharger located downstream of the engine.
With an inline six-cylinder engine having a front exhaust manifold divided from a rear exhaust manifold, the exhaust gases from the front three cylinders are isolated from the rear three cylinders. The exhaust gas exits both of the front and the rear exhaust manifolds into a turbocharger turbine inlet. The turbocharger turbine inlet may be a single, open channel, which allows the exhaust gases from the front and the rear exhaust manifolds to communicate. This communication of the exhaust gas, known as a “short circuit”, reduces the exhaust pulse energy and reduces the exhaust back pressure, reducing the engine braking power.
EGR systems also use exhaust back pressure to drive exhaust gas flow through the EGR system. However, as discussed above, an open turbocharger turbine inlet reduces the exhaust back pressure, which also reduces the drive of exhaust gas flow through the EGR system.
To address the reduced exhaust back pressure of an open turbocharger turbine inlet, a fully divided turbocharger turbine may be used. The divided turbocharger turbine has two isolated channels that prevent the communication of the exhaust gas from the front and rear engine cylinders. Wastegates are typically employed on turbochargers to regulate and protect the engine and turbocharger from excess boost pressure. In a fully divided turbocharger, typically there are two valves to waste the excess boost pressure instead of the one valve that is used in the open turbocharger. The fully divided turbocharger is also more expensive to develop and manufacture than the open turbocharger.